1 /*- 2 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #ifndef _SYS__RWLOCK_H_ 30 #define _SYS__RWLOCK_H_ 31 32 #include <machine/param.h> 33 34 /* 35 * Reader/writer lock. 36 * 37 * All reader/writer lock implementations must always have a member 38 * called rw_lock. Other locking primitive structures are not allowed to 39 * use this name for their members. 40 * If this rule needs to change, the bits in the reader/writer lock 41 * implementation must be modified appropriately. 42 */ 43 struct rwlock { 44 struct lock_object lock_object; 45 volatile uintptr_t rw_lock; 46 }; 47 48 /* 49 * Members of struct rwlock_padalign must mirror members of struct rwlock. 50 * rwlock_padalign rwlocks can use the rwlock(9) API transparently without 51 * modification. 52 * Pad-aligned rwlocks used within structures should generally be the 53 * first member of the struct. Otherwise, the compiler can generate 54 * additional padding for the struct to keep a correct alignment for 55 * the rwlock. 56 */ 57 struct rwlock_padalign { 58 struct lock_object lock_object; 59 volatile uintptr_t rw_lock; 60 } __aligned(CACHE_LINE_SIZE); 61 62 #endif /* !_SYS__RWLOCK_H_ */ 63